need more experienced advice

A picture is worth a 1000 words. How about attaching a rough sketch of the greenhouse as you have imagined it? It would help us visualize your idea.

 

You did not comment on the input you got earlier.
This is a discussion board where you can get some really professional advice about boat design. Not greenhouses! If you however have that knowledge to put in here, you will perhaps get somewhere here.

Since you also don’t seem to have a clue about how to grow crops there really no point in this.

I repeat my advice - This is a cool idea but you have approached it from the wrong side.

 

I'm a terrible artist
.....and i do mean terrible

 

A rough sketch is not art ...... just scribble

 

And rest of us are terrible gardeners, so your project probably ends here.

 

yea until i find a willing NA to work with

 

They are all willing..............

You would have to cope with some upfront cost though!

Most probably you would do much better with a project manager to start with.

 

Mangroves

Why don't you just grow mangrove trees on the deck? You just need a big tank of salt-water and a source of nutrients. They have edible "fruit" (actually air-root nodules, I think), leaves for tea, and you can use the wood as fuel (or even make another boat with it - it's good in salt water apparently).